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We study the critical temperature of a superconductive material in a weak external electric potential via a linear approximation of the BCS functional. We reproduce a similar result as in [Frank, Hainzl, Seiringer, Solovej, 2016] using the…

Mathematical Physics · Physics 2018-09-25 Rupert L. Frank , Christian Hainzl

By recognizing the vital importance of two-hole Cooper pairs (CPs) in addition to the usual two-electron ones in a strongly-interacting many-electron system, the concept of CPs was re-examined with striking conclusions. Based on this,…

Superconductivity · Physics 2009-11-11 M. de Llano , M. Grether

We establish universal behavior in temperature dependencies of some observables in $(s+id)$-wave BCS superconductivity in the presence of a weak $s$ wave. There also could appear a second second-order phase transition. As temperature is…

Strongly Correlated Electrons · Physics 2009-10-31 Angsula Ghosh , Sadhan K. Adhikari

In this letter we consider $D$-dimensional interacting Fermi liquids, and demonstrate that an attractive interaction with a finite range $R_s$ that is much greater than the Fermi wavelength $\lambda_F$ breaks the conventional BCS theory of…

Strongly Correlated Electrons · Physics 2025-02-18 Dmitry Miserev , Joel Hutchinson , Herbert Schoeller , Jelena Klinovaja , Daniel Loss

While it is known that the amplification of the superconducting critical temperature Tc is possible in a system of multiple electronic components in comparison with a single component system, many different road maps for room temperature…

In conventional superconductors, the pairing energy gap (\Delta) and superconducting phase coherence go hand-in-hand. As the temperature is lowered, both the energy gap and phase coherence appear at the transition temperature T_c. In…

We consider the Cooper-problem on a lattice model including onsite and near-neighbor interactions. Expanding the interaction in basis functions for the irreducible representation for the point group $C_{4v}$ yields a classification of the…

Superconductivity · Physics 2008-02-03 E. Otnes , A. Sudbø

We study heat transport in hybrid normal metal - superconductor - normal metal (NSN) structures. We find the thermal conductance of a short superconducting wire to be strongly enhanced beyond the BCS value due to inverse proximity effect.…

Superconductivity · Physics 2019-08-15 J. T. Peltonen , P. Virtanen , M. Meschke , J. V. Koski , T. T. Heikkilä , J. P. Pekola

We review the BCS to Bose Einstein condensation (BEC) crossover scenario which is based on the well known crossover generalization of the BCS ground state wavefunction $\Psi_0$. While this ground state has been summarized extensively in the…

Superconductivity · Physics 2011-09-13 Qijin Chen , Jelena Stajic , Shina Tan , Kathryn Levin

We address the thermodynamics, density profiles and superfluid density of trapped fermions undergoing BCS-BEC crossover, with and without population imbalance. Our approach represents a fully consistent treatment of "pseudogap effects",…

Strongly Correlated Electrons · Physics 2011-09-13 Yan He , Chih-Chun Chien , Qijin Chen , K. Levin

In addition to the conventional contribution that is directly controlled by the single-particle energy spectrum, the superfluid phase stiffness of a two-component Fermi gas has a geometric contribution that is governed by the quantum metric…

Quantum Gases · Physics 2019-02-05 M. Iskin

In a prior study of the boron isotope effect on the transition temperature ($T_c$) of $R$Ni$_2$B$_2$C ($R$ = Y, Lu) system, a positive isotope effect was observed, e.g., $T_{c}(^{10}B)> T_{c}(^{11}B)$. BCS theory predicts that the…

Superconductivity · Physics 2007-05-23 In-Sang Yang , M. V. Klein , S. Bud'ko , P. C. Canfield

The microscopic superconductivity theory in MgB2 systems in the magnetic fields directed parallel and perpendicular to the plane (ab) is built. The two energy bands of different dimensions overlapping on the Fermi surface (two-dimensional…

Superconductivity · Physics 2008-11-07 M. E. Palistrant , I. D. Cebotari , V. A. Ursu

Recent reflectivity measurements provide evidence for a "violation" of the in-plane optical integral in the underdoped high-T_c compound Bi_2Sr_2CaCu_2O_{8+\delta} up to frequencies much higher than expected by standard BCS theory. The sum…

Superconductivity · Physics 2009-11-07 T. Eckl , W. Hanke , E. Arrigoni

We first argue that the collective behaviour of the Cooper pairs created by thermal fluctuations well above the superconducting transition temperature, Tc, is dominated by the uncertainty principle which, in particular, leads to a…

We investigate the dependence of the energy gap ($G$) on the temperature ($T$) for the electron-doped high-temperature superconductors. The following compounds, in the form of the thin films, have been taken into consideration: $\rm…

Superconductivity · Physics 2016-11-22 R. Szczesniak , A. P. Durajski

In the last few years evidence has been accumulating that there are a multiplicity of energy scales which characterize superconductivity in the underdoped cuprates. In contrast to the situation in BCS superconductors, the phase coherence…

Superconductivity · Physics 2007-05-23 K. Levin , Qijin Chen , Ioan Kosztin , Boldizsar Janko , Ying-Jer Kao , Andrew Iyengar

The crossover from cooperative Cooper pairing to independent bound state (composite bosons) formation and condensation in quasi-2D systems is studied. It is shown that at low carrier density the critical superconducting temperature is equal…

Condensed Matter · Physics 2015-06-25 E. V. Gorbar , V. M. Loktev , S. G. Sharapov

Tunneling measurements of the temperature dependence of the electronic density of states (DOS) of ultrathin bilayers of Pb and Ag reveal that their superconducting energy gap, $\Delta (T)$, evolves similarly to BCS predictions despite the…

Superconductivity · Physics 2009-11-11 Zhenyi Long , M. D. Stewart , James M. Valles

Detailed temperature dependence of both superconducting gaps was obtained directly by means of SnS-Andreev spectroscopy. The \Delta \sigma,\pi(T) -curves were shown to be deviated from standard BCS-like behavior, due to k-space proximity…

Superconductivity · Physics 2012-04-24 S. A. Kuzmichev , T. E. Shanygina , S. N. Tchesnokov , S. I. Krasnosvobodtsev